/* -------------------------------------------------------------------------------

Copyright (C) 1999-2007 id Software, Inc. and contributors.
For a list of contributors, see the accompanying CONTRIBUTORS file.

This file is part of GtkRadiant.

GtkRadiant is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

GtkRadiant is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

----------------------------------------------------------------------------------

This code has been altered significantly from its original form, to support
several games based on the Quake III Arena engine, in the form of "Q3Map2."

------------------------------------------------------------------------------- */



/* marker */
#define TJUNCTION_C



/* dependencies */
#include "q3map2.h"




typedef struct edgePoint_s {
	float		intercept;
	vec3_t		xyz;
	struct edgePoint_s	*prev, *next;
} edgePoint_t;

typedef struct edgeLine_s {
	vec3_t		normal1;
	float		dist1;
	
	vec3_t		normal2;
	float		dist2;
	
	vec3_t		origin;
	vec3_t		dir;

	edgePoint_t	*chain;		// unused element of doubly linked list
} edgeLine_t;

typedef struct {
	float		length;
	bspDrawVert_t	*dv[2];
} originalEdge_t;

originalEdge_t	*originalEdges = NULL;
int				numOriginalEdges;
int				allocatedOriginalEdges = 0;


edgeLine_t		*edgeLines = NULL;
int				numEdgeLines;
int				allocatedEdgeLines = 0;

int				c_degenerateEdges;
int				c_addedVerts;
int				c_totalVerts;

int				c_natural, c_rotate, c_cant;

// these should be whatever epsilon we actually expect,
// plus SNAP_INT_TO_FLOAT 
#define	LINE_POSITION_EPSILON	0.25
#define	POINT_ON_LINE_EPSILON	0.25

/*
====================
InsertPointOnEdge
====================
*/
void InsertPointOnEdge( vec3_t v, edgeLine_t *e ) {
	vec3_t		delta;
	float		d;
	edgePoint_t	*p, *scan;

	VectorSubtract( v, e->origin, delta );
	d = DotProduct( delta, e->dir );

	p = safe_malloc( sizeof(edgePoint_t) );
	p->intercept = d;
	VectorCopy( v, p->xyz );

	if ( e->chain->next == e->chain ) {
		e->chain->next = e->chain->prev = p;
		p->next = p->prev = e->chain;
		return;
	}

	scan = e->chain->next;
	for ( ; scan != e->chain ; scan = scan->next ) {
		d = p->intercept - scan->intercept;
		if ( d > -LINE_POSITION_EPSILON && d < LINE_POSITION_EPSILON ) {
			free( p );
			return;		// the point is already set
		}

		if ( p->intercept < scan->intercept ) {
			// insert here
			p->prev = scan->prev;
			p->next = scan;
			scan->prev->next = p;
			scan->prev = p;
			return;
		}
	}

	// add at the end
	p->prev = scan->prev;
	p->next = scan;
	scan->prev->next = p;
	scan->prev = p;
}


/*
====================
AddEdge
====================
*/
int AddEdge( vec3_t v1, vec3_t v2, qboolean createNonAxial ) {
	int			i;
	edgeLine_t	*e;
	float		d;
	vec3_t		dir;

	VectorSubtract( v2, v1, dir );
	d = VectorNormalize( dir, dir );
	if ( d < 0.1 ) {
		// if we added a 0 length vector, it would make degenerate planes
		c_degenerateEdges++;
		return -1;
	}

	if ( !createNonAxial ) {
		if ( fabs( dir[0] + dir[1] + dir[2] ) != 1.0 ) {
			AUTOEXPAND_BY_REALLOC(originalEdges, numOriginalEdges, allocatedOriginalEdges, 1024);
			originalEdges[ numOriginalEdges ].dv[0] = (bspDrawVert_t *)v1;
			originalEdges[ numOriginalEdges ].dv[1] = (bspDrawVert_t *)v2;
			originalEdges[ numOriginalEdges ].length = d;
			numOriginalEdges++;
			return -1;
		}
	}

	for ( i = 0 ; i < numEdgeLines ; i++ ) {
		e = &edgeLines[i];

		d = DotProduct( v1, e->normal1 ) - e->dist1;
		if ( d < -POINT_ON_LINE_EPSILON || d > POINT_ON_LINE_EPSILON ) {
			continue;
		}
		d = DotProduct( v1, e->normal2 ) - e->dist2;
		if ( d < -POINT_ON_LINE_EPSILON || d > POINT_ON_LINE_EPSILON ) {
			continue;
		}

		d = DotProduct( v2, e->normal1 ) - e->dist1;
		if ( d < -POINT_ON_LINE_EPSILON || d > POINT_ON_LINE_EPSILON ) {
			continue;
		}
		d = DotProduct( v2, e->normal2 ) - e->dist2;
		if ( d < -POINT_ON_LINE_EPSILON || d > POINT_ON_LINE_EPSILON ) {
			continue;
		}

		// this is the edge
		InsertPointOnEdge( v1, e );
		InsertPointOnEdge( v2, e );
		return i;
	}

	// create a new edge
	AUTOEXPAND_BY_REALLOC(edgeLines, numEdgeLines, allocatedEdgeLines, 1024);

	e = &edgeLines[ numEdgeLines ];
	numEdgeLines++;

	e->chain = safe_malloc( sizeof(edgePoint_t) );
	e->chain->next = e->chain->prev = e->chain;

	VectorCopy( v1, e->origin );
	VectorCopy( dir, e->dir );

	MakeNormalVectors( e->dir, e->normal1, e->normal2 );
	e->dist1 = DotProduct( e->origin, e->normal1 );
	e->dist2 = DotProduct( e->origin, e->normal2 );

	InsertPointOnEdge( v1, e );
	InsertPointOnEdge( v2, e );

	return numEdgeLines - 1;
}



/*
AddSurfaceEdges()
adds a surface's edges
*/

void AddSurfaceEdges( mapDrawSurface_t *ds )
{
	int		i;
	

	for( i = 0; i < ds->numVerts; i++ )
	{
		/* save the edge number in the lightmap field so we don't need to look it up again */
		ds->verts[i].lightmap[ 0 ][ 0 ] = 
			AddEdge( ds->verts[ i ].xyz, ds->verts[ (i + 1) % ds->numVerts ].xyz, qfalse );
	}
}



/*
ColinearEdge()
determines if an edge is colinear
*/

qboolean ColinearEdge( vec3_t v1, vec3_t v2, vec3_t v3 )
{
	vec3_t	midpoint, dir, offset, on;
	float	d;

	VectorSubtract( v2, v1, midpoint );
	VectorSubtract( v3, v1, dir );
	d = VectorNormalize( dir, dir );
	if ( d == 0 ) {
		return qfalse;	// degenerate
	}

	d = DotProduct( midpoint, dir );
	VectorScale( dir, d, on );
	VectorSubtract( midpoint, on, offset );
	d = VectorLength ( offset );

	if ( d < 0.1 ) {
		return qtrue;
	}

	return qfalse;
}



/*
====================
AddPatchEdges

Add colinear border edges, which will fix some classes of patch to
brush tjunctions
====================
*/
void AddPatchEdges( mapDrawSurface_t *ds ) {
	int		i;
	float	*v1, *v2, *v3;

	for ( i = 0 ; i < ds->patchWidth - 2; i+=2 ) {
		v1 = ds->verts[ i ].xyz;
		v2 = ds->verts[ i + 1 ].xyz;
		v3 = ds->verts[ i + 2 ].xyz;

		// if v2 is the midpoint of v1 to v3, add an edge from v1 to v3
		if ( ColinearEdge( v1, v2, v3 ) ) {
			AddEdge( v1, v3, qfalse );
		}

		v1 = ds->verts[ ( ds->patchHeight - 1 ) * ds->patchWidth + i ].xyz;
		v2 = ds->verts[ ( ds->patchHeight - 1 ) * ds->patchWidth + i + 1 ].xyz;
		v3 = ds->verts[ ( ds->patchHeight - 1 ) * ds->patchWidth + i + 2 ].xyz;

		// if v2 is on the v1 to v3 line, add an edge from v1 to v3
		if ( ColinearEdge( v1, v2, v3 ) ) {
			AddEdge( v1, v3, qfalse );
		}
	}

	for ( i = 0 ; i < ds->patchHeight - 2 ; i+=2 ) {
		v1 = ds->verts[ i * ds->patchWidth ].xyz;
		v2 = ds->verts[ ( i + 1 ) * ds->patchWidth ].xyz;
		v3 = ds->verts[ ( i + 2 ) * ds->patchWidth ].xyz;

		// if v2 is the midpoint of v1 to v3, add an edge from v1 to v3
		if ( ColinearEdge( v1, v2, v3 ) ) {
			AddEdge( v1, v3, qfalse );
		}

		v1 = ds->verts[ ( ds->patchWidth - 1 ) + i * ds->patchWidth ].xyz;
		v2 = ds->verts[ ( ds->patchWidth - 1 ) + ( i + 1 ) * ds->patchWidth ].xyz;
		v3 = ds->verts[ ( ds->patchWidth - 1 ) + ( i + 2 ) * ds->patchWidth ].xyz;

		// if v2 is the midpoint of v1 to v3, add an edge from v1 to v3
		if ( ColinearEdge( v1, v2, v3 ) ) {
			AddEdge( v1, v3, qfalse );
		}
	}


}


/*
====================
FixSurfaceJunctions
====================
*/
#define	MAX_SURFACE_VERTS	256
void FixSurfaceJunctions( mapDrawSurface_t *ds ) {
	int			i, j, k;
	edgeLine_t	*e;
	edgePoint_t	*p;
	int			originalVerts;
	int			counts[MAX_SURFACE_VERTS];
	int			originals[MAX_SURFACE_VERTS];
	int			firstVert[MAX_SURFACE_VERTS];
	bspDrawVert_t	verts[MAX_SURFACE_VERTS], *v1, *v2;
	int			numVerts;
	float		start, end, frac, c;
	vec3_t		delta;
	
	
	originalVerts = ds->numVerts;
	
	numVerts = 0;
	for ( i = 0 ; i < ds->numVerts ; i++ )
	{
		counts[i] = 0;
		firstVert[i] = numVerts;

		// copy first vert
		if ( numVerts == MAX_SURFACE_VERTS ) {
			Error( "MAX_SURFACE_VERTS" );
		}
		verts[numVerts] = ds->verts[i];
		originals[numVerts] = i;
		numVerts++;

		// check to see if there are any t junctions before the next vert
		v1 = &ds->verts[i];
		v2 = &ds->verts[ (i+1) % ds->numVerts ];

		j = (int)ds->verts[i].lightmap[ 0 ][ 0 ];
		if ( j == -1 ) {
			continue;		// degenerate edge
		}
		e = &edgeLines[ j ];
		
		VectorSubtract( v1->xyz, e->origin, delta );
		start = DotProduct( delta, e->dir );

		VectorSubtract( v2->xyz, e->origin, delta );
		end = DotProduct( delta, e->dir );


		if ( start < end ) {
			p = e->chain->next;
		} else {
			p = e->chain->prev;
		}

		for (  ; p != e->chain ;  ) {
			if ( start < end ) {
				if ( p->intercept > end - ON_EPSILON ) {
					break;
				}
			} else {
				if ( p->intercept < end + ON_EPSILON ) {
					break;
				}
			}

			if ( 
				( start < end && p->intercept > start + ON_EPSILON ) ||
				( start > end && p->intercept < start - ON_EPSILON ) ) {
				// insert this point
				if ( numVerts == MAX_SURFACE_VERTS ) {
					Error( "MAX_SURFACE_VERTS" );
				}
				
				/* take the exact intercept point */
				VectorCopy( p->xyz, verts[ numVerts ].xyz );
				
				/* interpolate the texture coordinates */
				frac = ( p->intercept - start ) / ( end - start );
				for ( j = 0 ; j < 2 ; j++ ) {
					verts[ numVerts ].st[j] = v1->st[j] + 
						frac * ( v2->st[j] - v1->st[j] );
				}
				
				/* copy the normal (FIXME: what about nonplanar surfaces? */
				VectorCopy( v1->normal, verts[ numVerts ].normal );
				
				/* ydnar: interpolate the color */
				for( k = 0; k < MAX_LIGHTMAPS; k++ )
				{
					for( j = 0; j < 4; j++ )
					{
						c = (float) v1->color[ k ][ j ] + frac * ((float) v2->color[ k ][ j ] - (float) v1->color[ k ][ j ]);
						verts[ numVerts ].color[ k ][ j ] = (byte) (c < 255.0f ? c : 255);
					}
				}
				
				/* next... */
				originals[ numVerts ] = i;
				numVerts++;
				counts[ i ]++;
			}

			if ( start < end ) {
				p = p->next;
			} else {
				p = p->prev;
			}
		}
	}

	c_addedVerts += numVerts - ds->numVerts;
	c_totalVerts += numVerts;


	// FIXME: check to see if the entire surface degenerated
	// after snapping

	// rotate the points so that the initial vertex is between
	// two non-subdivided edges
	for ( i = 0 ; i < numVerts ; i++ ) {
		if ( originals[ (i+1) % numVerts ] == originals[ i ] ) {
			continue;
		}
		j = (i + numVerts - 1 ) % numVerts;
		k = (i + numVerts - 2 ) % numVerts;
		if ( originals[ j ] == originals[ k ] ) {
			continue;
		}
		break;
	}

	if ( i == 0 ) {
		// fine the way it is
		c_natural++;

		ds->numVerts = numVerts;
		ds->verts = safe_malloc( numVerts * sizeof( *ds->verts ) );
		memcpy( ds->verts, verts, numVerts * sizeof( *ds->verts ) );

		return;
	}
	if ( i == numVerts ) {
		// create a vertex in the middle to start the fan
		c_cant++;

/*
		memset ( &verts[numVerts], 0, sizeof( verts[numVerts] ) );
		for ( i = 0 ; i < numVerts ; i++ ) {
			for ( j = 0 ; j < 10 ; j++ ) {
				verts[numVerts].xyz[j] += verts[i].xyz[j];
			}
		}
		for ( j = 0 ; j < 10 ; j++ ) {
			verts[numVerts].xyz[j] /= numVerts;
		}

		i = numVerts;
		numVerts++;
*/
	} else {
		// just rotate the vertexes
		c_rotate++;

	}

	ds->numVerts = numVerts;
	ds->verts = safe_malloc( numVerts * sizeof( *ds->verts ) );

	for ( j = 0 ; j < ds->numVerts ; j++ ) {
		ds->verts[j] = verts[ ( j + i ) % ds->numVerts ];
	}
}





/*
FixBrokenSurface() - ydnar
removes nearly coincident verts from a planar winding surface
returns qfalse if the surface is broken
*/

extern void SnapWeldVector( vec3_t a, vec3_t b, vec3_t out );

#define DEGENERATE_EPSILON	0.1

int		c_broken = 0;

qboolean FixBrokenSurface( mapDrawSurface_t *ds )
{
	bspDrawVert_t	*dv1, *dv2, avg;
	int			i, j, k;
	float		dist;
	
	
	/* dummy check */
	if( ds == NULL )
		return qfalse;
	if( ds->type != SURFACE_FACE )
		return qfalse;
	
	/* check all verts */
	for( i = 0; i < ds->numVerts; i++ )
	{
		/* get verts */
		dv1 = &ds->verts[ i ];
		dv2 = &ds->verts[ (i + 1) % ds->numVerts ];
		
		/* degenerate edge? */
		VectorSubtract( dv1->xyz, dv2->xyz, avg.xyz );
		dist = VectorLength( avg.xyz );
		if( dist < DEGENERATE_EPSILON )
		{
			Sys_FPrintf( SYS_VRB, "WARNING: Degenerate T-junction edge found, fixing...\n" );

			/* create an average drawvert */
			/* ydnar 2002-01-26: added nearest-integer welding preference */
			SnapWeldVector( dv1->xyz, dv2->xyz, avg.xyz );
			VectorAdd( dv1->normal, dv2->normal, avg.normal );
			VectorNormalize( avg.normal, avg.normal );
			avg.st[ 0 ] = (dv1->st[ 0 ] + dv2->st[ 0 ]) * 0.5f;
			avg.st[ 1 ] = (dv1->st[ 1 ] + dv2->st[ 1 ]) * 0.5f;
			
			/* lightmap st/colors */
			for( k = 0; k < MAX_LIGHTMAPS; k++ )
			{
				avg.lightmap[ k ][ 0 ] = (dv1->lightmap[ k ][ 0 ] + dv2->lightmap[ k ][ 0 ]) * 0.5f;
				avg.lightmap[ k ][ 1 ] = (dv1->lightmap[ k ][ 1 ] + dv2->lightmap[ k ][ 1 ]) * 0.5f;
				for( j = 0; j < 4; j++ )
					avg.color[ k ][ j ] = (int) (dv1->color[ k ][ j ] + dv2->color[ k ][ j ]) >> 1;
			}
			
			/* ydnar: der... */
			memcpy( dv1, &avg, sizeof( avg ) );
			
			/* move the remaining verts */
			for( k = i + 2; k < ds->numVerts; k++ )
			{
				/* get verts */
				dv1 = &ds->verts[ k ];
				dv2 = &ds->verts[ k - 1 ];
				
				/* copy */
				memcpy( dv2, dv1, sizeof( bspDrawVert_t ) );
			}
			ds->numVerts--;
			
			/* after welding, we have to consider the same vertex again, as it now has a new neighbor dv2 */
			--i;

			/* should ds->numVerts have become 0, then i is now -1. In the next iteration, the loop will abort. */
		}
	}
	
	/* one last check and return */
	return ds->numVerts >= 3;
}









/*
================
EdgeCompare
================
*/
int EdgeCompare( const void *elem1, const void *elem2 ) {
	float	d1, d2;

	d1 = ((originalEdge_t *)elem1)->length;
	d2 = ((originalEdge_t *)elem2)->length;

	if ( d1 < d2 ) {
		return -1;
	}
	if ( d2 > d1 ) {
		return 1;
	}
	return 0;
}



/*
FixTJunctions
call after the surface list has been pruned
*/

void FixTJunctions( entity_t *ent )
{
	int					i;
	mapDrawSurface_t	*ds;
	shaderInfo_t		*si;
	int					axialEdgeLines;
	originalEdge_t		*e;
	bspDrawVert_t	*dv;
	
	/* meta mode has its own t-junction code (currently not as good as this code) */
	//%	if( meta )
	//%		return; 
	
	/* note it */
	Sys_FPrintf( SYS_VRB, "--- FixTJunctions ---\n" );
	numEdgeLines = 0;
	numOriginalEdges = 0;
	
	// add all the edges
	// this actually creates axial edges, but it
	// only creates originalEdge_t structures
	// for non-axial edges
	for ( i = ent->firstDrawSurf ; i < numMapDrawSurfs ; i++ )
	{
		/* get surface and early out if possible */
		ds = &mapDrawSurfs[ i ];
		si = ds->shaderInfo;
		if( (si->compileFlags & C_NODRAW) || si->autosprite || si->notjunc || ds->numVerts == 0 )
			continue;
		
		/* ydnar: gs mods: handle the various types of surfaces */
		switch( ds->type )
		{
			/* handle brush faces */
			case SURFACE_FACE:
				AddSurfaceEdges( ds );
				break;
			
			/* handle patches */
			case SURFACE_PATCH:
				AddPatchEdges( ds );
				break;
			
			/* fixme: make triangle surfaces t-junction */
			default:
				break;
		}
	}

	axialEdgeLines = numEdgeLines;

	// sort the non-axial edges by length
	qsort( originalEdges, numOriginalEdges, sizeof(originalEdges[0]), EdgeCompare );

	// add the non-axial edges, longest first
	// this gives the most accurate edge description
	for ( i = 0 ; i < numOriginalEdges ; i++ ) {
		e = &originalEdges[i];
		dv = e->dv[0]; // e might change during AddEdge
		dv->lightmap[ 0 ][ 0 ] = AddEdge( e->dv[ 0 ]->xyz, e->dv[ 1 ]->xyz, qtrue );
	}

	Sys_FPrintf( SYS_VRB, "%9d axial edge lines\n", axialEdgeLines );
	Sys_FPrintf( SYS_VRB, "%9d non-axial edge lines\n", numEdgeLines - axialEdgeLines );
	Sys_FPrintf( SYS_VRB, "%9d degenerate edges\n", c_degenerateEdges );

	// insert any needed vertexes
	for( i = ent->firstDrawSurf; i < numMapDrawSurfs ; i++ )
	{
		/* get surface and early out if possible */
		ds = &mapDrawSurfs[ i ];
		si = ds->shaderInfo;
		if( (si->compileFlags & C_NODRAW) || si->autosprite || si->notjunc || ds->numVerts == 0 || ds->type != SURFACE_FACE )
			continue;
		
		/* ydnar: gs mods: handle the various types of surfaces */
		switch( ds->type )
		{
			/* handle brush faces */
			case SURFACE_FACE:
				FixSurfaceJunctions( ds );
				if( FixBrokenSurface( ds ) == qfalse )
				{
					c_broken++;
					ClearSurface( ds );
				}
				break;
			
			/* fixme: t-junction triangle models and patches */
			default:
				break;
		}
	}
	
	/* emit some statistics */
	Sys_FPrintf( SYS_VRB, "%9d verts added for T-junctions\n", c_addedVerts );
	Sys_FPrintf( SYS_VRB, "%9d total verts\n", c_totalVerts );
	Sys_FPrintf( SYS_VRB, "%9d naturally ordered\n", c_natural );
	Sys_FPrintf( SYS_VRB, "%9d rotated orders\n", c_rotate );
	Sys_FPrintf( SYS_VRB, "%9d can't order\n", c_cant );
	Sys_FPrintf( SYS_VRB, "%9d broken (degenerate) surfaces removed\n", c_broken );
}
